No reason to say a 1200 is any better than a 4000, really, they'll both run the same games and software, but the 4000 starts off with a faster processor and is easier to expand. If yours works, it's probably ready to run WHDload which is really all you need these days, while a basic 1200 would require some upgrading first to run it well.
I personally didn't see the point in owning both, one is as good as the other to me unless you're in a really cramped area that calls for a 1200-sized machine.
